Cationic ring-opening polymerization poly

The cationic ring opening polymerization of oxolane (THF) or of N-substituted aziridines can be initiated by oxocarbenium salts [42]. The methacrylic ester unsaturation is insensitive to cationic sites, and polyoxolanes (poly-THF) macromonomers are obtained in good yields. 

By utilizing a combination of RAFT and cationic ROP, the synthesis of [poly(methyl methacrylate)][poly(l,3-dioxepane)][polystyrene] miktoarm star terpolymers was achieved [182], The approach involved the synthesis of PS functionalized with a dithiobenzoate group by RAFT polymerization and subsequent reaction with hydroxyethylene cinnamate (Scheme 98). The newly created hydroxyl group was then used for the cationic ring opening polymerization of 1,3-dioxepane (DOP). The remaining dithiobenzoate group was used for the RAFT polymerization of methyl methacrylate. 

SPOCC resin is based on the cross-linking of long-chain Poly(ethylene glycol) (PEG)terminally substituted with oxetane by cationic ring-opening polymerization. 

Becer CR, Paulus RM, Hoppener S et al. (2008) Synthesis of poly(2-ethyl-2-oxazoline)-h-poly(styrene) copolymers via a dual initiator route combining cationic ring opening polymerization and atom transfer radical polymerization. Macromolecules 41 5210-5215... 

Finally, cationic ring-opening polymerization of 2-aIkoxy-5(4//)-oxazolones has been used to prepare poly iV-alkoxycarbonyl amino acids. The polymerization was found to be dependent on the nature of the amino acid side chain and the substituent on C-2. 

We recently investigated a different route for the synthesis of poly(IB-h-f-CL) diblock and poly( -CL-fo-IB-fo- -CL) triblock copolymers by site-transformation of living cationic polymerization of IB to cationic ring-opening polymerization of -CL via the activated monomer mechanism [95]. 

Takata et al. [99] found for two spiro orthocarbonates (119 and 121) having l,4,6,9-tetraoxaspiro[6.6]tridecane skeletons different cationic ring-opening polymerization behavior Irrespective of solvent, initiator, and temperature (from room temperature to 150°C), 119 gave polycarbonate (120), whereas 121 gave poly (ether-carbonate) (122). 

Linear PEI can be obtained by cationic ring-opening polymerization of 2-oxazoline, followed by alkaline hydrolysis of the resulting poly(N-formylethyleneimine)9). 

Poly(N-alkyl-ethylene imine) can be prepared by cationic ring-opening polymerization of N-alkylaziridines however, branched polymers are obtained by this way 19>. Linear poly-MEI may be obtained by N-methylation of linear PEI by the Clarke-Eschiweiler variation of the Leukart reaction, in which an excess of formic acid is used together with formaldehyde. The reaction may be performed either on PEI, or... 

Higher homologs of PEI can be obtained by cationic ring-opening polymerization of azetidine monomers21). Polymers of this kind can also be N-methylated as previously described in the case of PEI. The cationic polymerization of N-substituted azetidines may give rise to poly(tertiary amine)s. Linear poly(tertiary amine)s have been obtained by selective dealkylation of poly(quaternary ammonium salt)s22). 

This review summarizes all the data we obtained on the synthesis and cationic ring-opening polymerization of bicyclic acetals and orthoesters, and discusses the relationship between ring-strain and poly-merlzablllty. This ties In with earlier work on the polymerlzabll-Ity of monocyclic and bicyclic lactams ( - ). A new mechanism for the propagation step In the polymerization of bicyclic orthoesters Is supported. 

FIGURE 3.6 Cationic ring-opening polymerization (CROP) of meso-lactic acid dimer toward poly(D,L-lactide). 

The polymer can be spun into an elastic yam of very fine denier. It is also claimed to exhibit good mechanical properties for molding and compares favorably with commercial polyesters and nylons. Also, polycaprolactone was reported to be used in some medical applications in biodegradable surgical sutures and postoperative support pins and splints. Similar uses are also found for two other polyesters, poly (lactic acid) and poly(glycolic acid). The two polymers form from their cyclic dimers by cationic ring-opening polymerizations with the aid of Lewis acids ... 

Other cationic ring opening polymerizations can also be transformed to ATRP to yield block copolymers [439], Thus, formation of block copolymers was initiated by poly(tetramethylene glycol) containing one bromopropionyl end group. These were used to form block copolymers by ATP polymerization of styrene, methyl methacrylate, and methyl acrylate. 

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